A dual surface inorganic molecularly imprinted Bi2WO6-CuO/Ag2O heterostructure with enhanced activity-selectivity towards the photocatalytic degradation of target contaminants

Abstract

In this work, a high-surface-area dual inorganic molecularly imprinted (DIMI) Bi₂WO₆/CuO/Ag₂O photocatalyst was developed for the selective photocatalytic degradation of methyl green (MG) and auramine O (AO) dyes as target pollutants. The DIMI-Bi₂WO₆/CuO/Ag₂O heterojunction was synthesized by a sonochemically assisted sol–gel method by coating a layer of molecularly imprinted Ag₂O/CuO on the surface of Bi₂WO₆ nanocubes with MG and AO as the templates. This was followed by calcination for the removal of target molecules and annealing for Ag/Cu oxide preparation. This novel photocatalyst was prepared to overcome the challenge of the co-existing non-target molecules, which has limited the photocatalytic degradation performance. The surface DIMI sites could act as surface defects for accelerating the separation of photogenerated holes and electrons, which led to the increased generation of OH radicals. Moreover, the DIMI sites had increased binding affinity toward MG and AO via the formation of multiple H bonds and electrostatic bonds, which were confirmed by FTIR spectroscopy, PL and EIS studies. The surface DIMI sites led to the increased adsorption and improved local concentration of MG and AO on Bi₂WO₆/CuO/Ag₂O. Consequently, the heterojunction properties of the final DIMI product accelerated the transfer and separation of photogenerated carriers. The high binding affinity of the DIMI sites to MG and AO confirmed the selective recognition, which was tested in the presence of coexisting pollutant dyes. The other characterizations confirmed the successful fabrication and high photocatalytic activity of the high-surface-area DIMI-Bi₂WO₆/CuO/Ag₂O heterostructured composite. In general, the superior interfacial electronic interactions, high migration efficiency of photoinduced charge carriers, and strong visible light absorption of the prepared photocatalyst resulted in good photocatalytic performance.